network level failure with MELCO 11Mb card

[text-mangling by the input box on the web-page]
I have two Melco WLI-PCM-L11 cards, which are (I believe) clones of the WaveLAN cards for the Japanese market. I am trying to get them working as peers in an Ad-Hoc network. I have the cards and the pcmcia interaction okay - inserting the card brings up the interface and the wireless extensions look okay. I just cannot seem to get the cards to 'hear' each other.
My two hosts are 'A' and 'B'. In each machine, the Melco card is setup as eth1. Both machines are redhat 6.2 installs, with the 3.1.13 pcmcia bundle on top (1.0.4 wavelan gpl driver).
The /etc/pcmcia/config.opts line for the wvlan_cs driver is something like:
module "wvlan_cs" opts "eth=1 port_type=3 network_name=01020304050607 channel=14"
(station name only is different). All other settings are the default. rate is set to auto.
a# ifconfig eth1 ; iwconfig eth1
eth1 Link encap:Ethernet HWaddr 00:60:1D:AA:AA:AA
inet addr:10.10.10.1 Bcast:10.10.10.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1 errors:0 dropped:0 overruns:0 frame:0
TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
Interrupt:10 Base address:0x100
eth1 IEEE 802.11-DS ESSID:"01020304050607" Nickname:"A"
Frequency:2.484GHz Sensitivity:1/3 Mode:Ad-Hoc
Access Point: 00:00:00:00:00:00
Bit Rate:2Mb/s RTS thr:off Fragment thr:off
Encryption key:off
Power Management:off
Link quality:0 Signal level:0 Noise level:0
Rx invalid nwid:0 invalid crypt:0 invalid misc:0
b# ifconfig eth1 ; iwconfig eth1
eth1 Link encap:Ethernet HWaddr 00:60:1D:BB:BB:BB
inet addr:10.10.10.2 Bcast:10.10.10.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
Interrupt:3 Base address:0x100
eth1 IEEE 802.11-DS ESSID:"01020304050607" Nickname:"B"
Frequency:2.484GHz Sensitivity:1/3 Mode:Ad-Hoc
Access Point: 00:00:00:00:00:00
Bit Rate:2Mb/s RTS thr:off Fragment thr:off
Encryption key:off
Power Management:off
Link quality:0 Signal level:0 Noise level:0
Rx invalid nwid:0 invalid crypt:0 invalid misc:0
In both 'A' and 'B' the cards seem okay, the power light is on, and the interface is up. When I try to ping out of one interface to the other there is a blinking on the data led of the sender. When I tcpdump the interface I do see the arp requests going out.
The problem is that although I appear to be able to send I cannot receive any data on the other card. The link/signal/noise readings all sit at zero. The cards appear to be deaf.
Is there something obvious that I can try to make the connection work ? I must be missing something simple, but I cannot work out what.
Thanks,
Jonathon